The reaction mechanism of the cyanide-catalyzed benzoin condensation without protonic solvent assistance has been studied computationally for the first time employing the density functional theory (B3LYP) method in conjunction with 6-31+G(d,p) basis set. Four possible pathways have been investigated. A new proposed pathway on the basis of the Lapworth mechanism is determined to be the dominant pathway in aprotic solvent, in which the formation of the Lapworth's cyanohydrin intermediate is a sequence including three steps assisted by benzaldehyde, clearly manifesting that the reaction can take place in aprotic solvents such as DMSO. In this favorable pathway with six possible transition states located along the potential energy surface, the reaction of the cyanide/benzaldehyde complex with another benzaldehyde to afford an alpha-hydroxy ether is the rate-determining dynamically with the activation free energy barrier of 26.9 kcal/mol, and the step to form cyanohydrin intermediate from alpha-hydroxy ether is partially rate-determining for its relatively significant barrier 20.0 kcal/mol.

Affiliation

College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education and State Key Laboratory of Biotherapy, Sichuan University, Chengdu 610064, People's Republic of China.

The detailed mechanism of the cyanide catalyzed synthesis of benzoxazole from 2-aminophenol and benzaldehyde was investigated in depth using Density Functional Theory (DFT). The metal-free aerobic oxi...

Mechanistic study has been carried out on the B(C6F5)3-catalyzed amine alkylation with carboxylic acid. The reaction includes acid-amine condensation and amide reduction steps. In condensation step, t...

Although aldol condensation is one of the most important organic reactions, capable of forming new C-C bonds, its mechanism has never been fully established. It is now concluded that the rate-limiting...

A new method for the synthesis of 2-vinylindole-3-acetic acid derivatives from aldimines, which are derived from 2-aminocinnamic acid derivatives and alpha,beta-unsaturated aldehydes, via a cyanide-ca...

The intermolecular or intramolecular asymmetric benzoin reaction was catalyzed by a small amount of N-heterocyclic carbene (NHC) (0.2-1 mol %) under solvent-free conditions. The solvent-free intramole...

The purpose of this research is to investigate how using different methods to reduce the
energy density of entrees affects daily energy intake in adults. It is hypothesized that
reducing t...

Medical and Biotech [MESH] Definitions

Benzoin

A white crystalline compound prepared by condensation of benzaldehyde in potassium cyanide and used in organic syntheses. This should not be confused with benzoin gum from STYRAX.

Lindera

A plant genus in the LAURACEAE family. Lindera benzoin is a source of a balsamic resin called benzoin which is up to 1/3 BENZOIC ACID. This should not be confused with the chemical BENZOIN or the plant STYRAX BENZOIDES.

Hydrogen Cyanide

Hydrogen cyanide (HCN); A toxic liquid or colorless gas. It is found in the smoke of various tobacco products and released by combustion of nitrogen-containing organic materials.

Centrifugation, Density Gradient

Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Bone Density

The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.